>r. Gyrus Aaier, 



Librarian U. S. Nat. Museum. 



JUNE, 1910. 



Established by BENJAMIN SILLIMAN in 1818. 



THE 



AMERICAN 



JOURNAL OF SCIENCE 



Editor: EDWAED S. DANA. 



ASSOCIATE EDITORS 



Professors GEOEGE L. GOODALE, JOHN TKOWBKIDGE, 

 W. G. FAKLOW and WM. M. DAVIS, of Cambridge, 



Professors ADDISON E. VEKKILL, HOKACE L. WELLS, 

 L. V. PIKSSON and H. E. GEEGOEY, of New Haven, 



Professor HENEY S. WILLIAMS, of Ithaca, 

 Professor JOSEPH S. AMES, of Baltimore, 

 Mr. J. S. DILLEE, of Washington. 



FOURTH SERIES 



YOL. XXIX— [WHOLE NUMJBEB, CLXX1X.] 

 No. 174— JUNE, 1910. 



WITH PLATES II-V. 



NEW HAVEN, CONNECTICUT. 



1910. 



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